Apparatus for controlling the power output of a nuclear reactor

Abstract

A nuclear reactor, such as advanced pressurized water reactor, with controlled power output includes a reactor core having a cross section in a given plane with a center of area and axes of symmetry passing through the center of area. A multiplicity of control elements are disposed in groups, each having at least one of the control elements. The control elements of each of the groups with more than one control element are joined together. The groups are symmetrical to at least two of the axes of symmetry. Drive mechanisms each move a respective one of the groups of control elements. Each of the control elements has a plurality of control rods. A support structure joins the control rods to one another. Fuel assemblies are disposed in groups. Each of the groups of control elements has a given number of control elements being associated with one of the groups of fuel assemblies having the given number of fuel assemblies. Other fuel assemblies with which the control elements are not associated surround the groups of fuel assemblies.

We claim: 
     
       1. Nuclear reactor with controlled power output, comprising a reactor core having a cross section in a given plane with a center of area and axes of symmetry passing through the center of area, a multiplicity of control elements disposed in groups, each of said groups having more than one of said control elements, means for joining together said control elements of each of said groups, said groups being symmetrical to at least two of the axes of symmetry,   drive mechanisms each moving a respective one of said groups of control elements,   each of said control elements having a plurality of control rods,   a support structure joining said control rods of a control element to one another,   fuel assemblies disposed in groups, each of said groups of control elements having a given number of control elements being associated with one of said groups of fuel assemblies having the given number of fuel assemblies, and   other fuel assemblies with which said control elements are not associated, said other fuel assemblies surrounding said groups of fuel assemblies.   
     
     
       2. Nuclear reactor according to claim 1, wherein each of said groups of control elements has at most three control elements, and each of said groups of fuel assemblies has at most three fuel assemblies. 
     
     
       3. Nuclear reactor according to claim 2, wherein the cross section of said reactor core is approximately circular, and each two of said axes of symmetry define an angle therebetween being an integral multiple of 30°. 
     
     
       4. Nuclear reactor according to claim 1, wherein the cross section of said reactor core is substantially circular, and said reactor core has a hexagonal fuel rod grid structure. 
     
     
       5. Nuclear reactor according to claim 1, wherein said groups of control elements are a total of 61 groups of control elements having a total of 151 control elements, 13 of said groups of control elements each have one control element,   6 of said groups of control elements each have two control elements, and 42 of said groups of control elements each have three control elements.   
     
     
       6. Nuclear reactor according to claim 1, including connecting pieces each having said control elements of a respective one of said groups detachably retained thereon and each being movable by a respective one of said drive mechanisms. 
     
     
       7. Nuclear reactor according to claim 6, including a multi-armed guide plate in which said connecting piece is guided. 
     
     
       8. Nuclear reactor according to claim 7, wherein said multi-armed guide plate has adjacent arms defining an angle therebetween being a fraction of 360°, said fraction corresponding to the number of said arms. 
     
     
       9. Advanced pressurized water nuclear reactor with controlled power output, comprising a reactor core having a cross section in a given plane with a center of area and axes of symmetry passing through the center of area, a multiplicity of control elements disposed in groups, each of said groups having more than one of said control elements, said control elements of each of said groups being joined together, said groups being symmetrical to at least two of the axes of symmetry,   drive mechanisms each moving a respective one of said groups of control elements,   each of said control elements having a plurality of control rods,   a support structure joining said control rods of a control element to one another,   fuel assemblies disposed in groups, each of said groups of control elements having a given number of control elements being associated with one of said groups of fuel assemblies having the given number of fuel assemblies, and   other fuel assemblies with which said control elements are not associated, said other fuel assemblies surrounding said groups of fuel assemblies.